Just wondering why the the Sigma Sport 150/600 is not on the list. I went through the comparison process a couple of years ago; I've been rather happy with it on my d800. I don't recall the Nikon 200-500 being around when I got it so don't know how they compare. It seems to be quite sharp but does need lots of light. I've even gotten some good BIF shots. There were better lens available but this seemed the best value for me. YMMV...